Please read the abstract in the section 00front of this document / Dissertation (MChD (Orthodontics))--University of Pretoria, 2007. / Orthodontics / unrestricted

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Selection differentials and selection indices in retrospect were calculated to determine the relative emphasis placed on production and type traits through bull selection. Indices in retrospect including only production traits indicated that, for Holsteins, fat yield was the trait most heavily selected for between 1978 and 1987, followed by protein percent and then milk yield. Fat percent and protein yield had negative index weights throughout the nine year period. In Ayrshires, similar weights were observed except that milk yield index weights were negative throughout the nine year period. It was found that the relative weight placed on type was small and did not affect the relative weights place on production traits. Within Holsteins, differences in bull selection when multiple services were required to successfully service a cow indicated that selection for overall size was reduced in later services. Within Ayrshires, there were no differences in any production or type trait within multiple services.

Thesis (Ph. D.)--Drexel University, 1985. / Vita. Description based on print version record. Includes bibliographical references (leaves 182-185).

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Multilayer paint is a significant fire hazard particularly concerning rapid spread of flame,smoke and toxic species production. Fire protective coatings are often employed to protect this unpredictably flammable substrate from ignition (for example resulting from arson attacks in the communal areas of multi- occupancy buildings). Literature shows a gap in the understanding of this problem,a lack of suitable flammability tests,and methods for screening new fire protective coatings required to address this problem. This work investigates the factors affecting coating performance and develops screening test methods to estimate protection performance in standard fire tests. The dependence of these tests has been investigated with regard to substrate, coating thickness,composition of coating, thermal conductivity and rheological properties, to inform the development of modified coating formulations with enhanced fire safety.Coating materials have been investigated using thermogravimetric ana lysis (TGA) in both air and inert atmospheres and their burning behaviour using the cone calorimeter (ISO 5660). Novel screening test methods also include a test adapted from BS EN 367 for measurement of thermal conductivity, a thermocouple embedded in cone samples to assess the temperature profile at the substrate-coating interface and BS 476: Part 6 (adapted) as a scaled down version of the standard fire test. The chemical changes occurring during burning of current coatings formulations were investigated using CHN analysis, pyrolysis gas chromatography coupled with mass spectrometry (pyGC-MS),inductively coupled plasma coupled with mass spectrometry (ICP-MS),diamond attenuated total reflectance coupled with fourier transform infra-red (dATR-FTIR),nuclear magnetic resonance (NMR} and scanning electron microscopy coupled with electron dispersive X-ray analysis (SEM-EDAX} to inform the development of novel formulations. Generally,intumescent formulations tend to exhibit lower fire propagation indexes when assessed in the BS 476: Part 6,longer time to ignition and lower peak heat release rates in the cone calorimeter, as well as reduced thermal conductivity recorded in the BS EN 367. Results report mixed performance,suggesting that it is not only char residue formation that ensures a pass in the standard fire tests. Rheological properties of the coatings are crucial to performance,with softening temperature and reduction in viscosity coinciding with gas release of the fire retardant additive. Each screening test method assesses one particular aspect of flammability, they are dependent on the controlled conditions under which results are collected,and the limited correlation observed with the performance in the standard fire tests, do not conclusively predict performance in a real fire situation.

Cluster is not a new phenomenon, having existed in different forms for a long time. Although a large amount of work has been dedicated to cluster research (Marshall, 1920; Krugman, 1995; Schmitz 1997; Porter, 1998; Wilson and Popp, 2003), there is still a lack of convincing explanations as to how and why clusters are created. Reviewing the different definitions of ‘cluster’ from previous studies, produces the interesting finding that most of the cluster definitions neglect one key element – the ‘actor’ – that is, the individuals who are involved in the process of founding new businesses that give rise to cluster formation. Recognising the values and shortcomings of the extant studies on clusters, this thesis aims to establish a conceptual framework and attempt to advance the understanding of the cluster formation process from an alternative view. The purpose is to answer the research questions of how and why cluster are formed, how different actors interact with key institutional factors relevant to cluster creation and how these actors themselves make sense of the cluster creation process, particularly in the Chinese context. This research employs a qualitative approach comprising semi-structured in-depth interviews, which seek to uncover the depth and richness of the living experiences of different actors with the SME clusters. Fieldwork was completed in multi-phases involving a preliminary data collection in phase one, followed by a further data collection in the second and subsequent phases through re-interviewing the key informants. The findings of the three empirical case studies echoed the claims that the very notion of a cluster is a dynamic, and for some a ‘Chaotic’ one (Martin and Sunley, 2003). This highlights the importance of a comprehensive framework to address the complex web of elements that are involved in cluster formation. The result of the thesis also indicates that individual (entrepreneurs & social relations), and the social interactions among individuals and their institutional context are the key ingredients for forming clusters. It is suggested that the established conceptual framework, based upon the theories of institutionalisation, social embeddedness and sensemaking, can help to fill the gap in the extant cluster research and pave the way for future research.

This thesis presents a narrative that connects discussion of a number of my papers submitted for consideration of the award of PhD by published work with reflections on methods and theory within a critical sociological context. This analysis of my publications is extended by a critical engagement with communicative action theory to consider its relevance for thinking about service user involvement activity in university settings. The thesis explores methodological and theoretical ideas by first narrating the thematic consistency of the portfolio of published work presented for consideration and, second, considering analytic connections with wider critical social theory and emancipatory goals. In part this is accomplished by exploring a scholarly interest in the subjective: tracing in my own papers a development of thought from an affinity for critical post-structuralist concepts of a de-centred subject, as illustrated in my use of Q-methodology as a particular means of accessing forms of subjective expression, through to a current interest in forms of critical social theory, aligned to the Frankfurt School. Despite some acknowledged philosophical tensions, it is argued that there is a consistency of theoretical exposition whereby a line of reasoning via Habermas’s theory of communicative action, focuses on a radical subjectivity which is not antithetical to the aforementioned post-structural accounts. A contribution to original knowledge is demonstrated with respect to theorising social constructions of difference and identity in a mental health context and critical analyses and commentary on the mental health service user/survivor movement. Themes of radicalism and emancipation in research methods and praxis, and their critique, connect with a concluding focus on academic alliances with user movement activists including an analytic reflection on the university as a particular social space which may be amenable to forging effective solidarity.

The current research examined gaming within a leisure context to examine the motivational and experiential value of the activity, to better understand the range of outcomes of playing videogames. Flow theory was used as a theoretical framework for examining positive gaming experiences, and how these were associated with gaming motivations, and potential positive psychological and affective outcomes. The research utilised a mixed-methodological approach with samples of gamers. These included focus groups, an experiment and online questionnaires. The findings showed that immersion and achievement-orientated gaming motivations predicted flow in gaming, and could also predict some dimensions of psychological well-being. Flow in gameplay interacted with increases in positive mood and activation. This suggests that the processes involved in gaming are influential to positive gaming outcomes. Specific game aspects were influential to the nature of gaming experiences, although these were largely dependent on game-type. The findings also showed that social gaming contexts were influential towards gaming experiences, and the associated affective outcomes. This suggests the dynamic nature of gaming experiences, and the importance of acknowledging the wider social contexts in which gaming occurs. Aspects of personality (i.e. trait aggression and competitiveness) influenced negative mood after gameplay, suggesting the importance of considering internal factors when examining gaming outcomes. Further, because gaming motivations, experiences and the associated effects were largely individual and game-specific, this highlights the need for future research to adopt more idiographic approaches. Based on the findings, the research presents a Process Model of Gameplay to examine the dynamic nature of gameplay processes for a range of outcomes. The current research highlights the effectiveness of considering gaming within the wider context of leisure, to identify gaming processes as a way of examining the influence of gaming motivations and experiences on positive outcomes of the activity.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management